With the latest developments in both the automotive and communications industries, especially concerning the emerging 5G networks, IoV, and the adoption of Vehicle-to-Everything (V2X) connectivity, there has been a shift towards the establishment of Heterogeneous Vehicular Networks (HetVNets) environments. The rapid growth of data traffic and the drastic expansion of heterogeneous network infrastructure have resulted in a significant increase in energy consumption within wireless communication systems. Balancing energy efficiency and spectral efficiency has become a major challenge in Heterogeneous Vehicular networks, particularly concerning energy optimization, making the design of network systems considerably more challenging. Therefore, this paper attempts to optimize the energy utilized for each packet transmission, considering its stochastic nature and the optimized control parameters of two meta-heuristic algorithms-Particle Swarm Optimization and Artificial Bee Colony Optimization. The optimization process is executed using the Particle Bee Colony Swarm algorithm. Subsequently, a comparison is made with other proposed algorithms, namely LDOD, FO, RO, and MATO, in terms of energy efficiency and spectral efficiency. The performance analysis reveals that the numerical results outperform existing algorithms, demonstrating a 30.32% increase in spectral efficiency and 73.25% increase in energy efficiency.

The demand for passenger transportation, especially by road, has been increasing due to globalisation, resulting in further delays and traffic congestion. This paper addresses issues to minimise delays and traffic congestion using source and destination information in an urban environment. A journey is defined as the traversal of several road links and junctions. The delays on the links are analysed using M/M/K Markov technique. The delays at a junction are examined using the Zero-Server Markov Chain technique. In order to study multiple junctions, this technique is combined with the Jackson Network model. This combined approach is then used to evaluate the delays at multiple junctions using the Middlesex University VANET Testbed (a real-time vehicular network in London, UK). Initial results indicate that there is more congestion at traffic junctions and hence the Markov Chain analysis will allow better traffic algorithms to reduce congestion at traffic junctions, resulting in reduced journey times as well as less congestion.

Mobile Cloud Computing enables the migration of services to the edge of Internet. Therefore, high performance computing clusters are widely deployed to improve computational capabilities of such environments. However, they are prone to failures and need analytical models to predict their behavior in order to deliver desired quality-of-service and quality-of-experience to mobile users. This article proposes a 3D analytical model and a problem-solving approach for sustainability evaluation of high-performance computing clusters. The proposed solution uses an iterative approach to obtain performance measurements to overcome the state space explosion problem. The availability modeling and evaluation of master and computing nodes are performed using a multi-repairman approach. The optimum number of repairmen is also obtained to get realistic results and reduce the overall cost. The proposed model is validated using discrete event simulation. The analytical approach is much faster and in good agreement with the simulations. The analysis focuses on mean queue length, throughput and mean response time outputs. The maximum differences between analytical and simulation results in the considered scenarios of up to a billion states are less than 1.149, 3.82, and 3.76 percent, respectively. These differences are well within the 5 percent of confidence interval of the simulation and the proposed model.

In order to provide ubiquitous communication, seamless connectivity is now required in all environments including highly mobile networks. By using vertical handover techniques, it is possible to provide uninterrupted communication as connections are dynamically switched between wireless networks as users move around. However, in a highly mobile environment, traditional reactive approaches to handover have been found to be inadequate. Therefore, the proactive handover techniques are actively being investigated in the context of next generation mobile networks. This paper presents a new methodology to support proactive resource allocation for emerging future networks such as 5G by allowing base stations to calculate the probability of contention based on the demand for network resources. The proposed approach uses Markov chains to model the contention and results are obtained showing enhanced system performance in terms of throughput and mean response time.

This paper carries out a study on enforcing trust as a means to improve user adoption of wearable technologies. These technologies can play an integral part in facilitating intelligent environments by collecting real-time data for input into networked controllers. The paper reviews wearable devices, their use and current concerns and challenges as well as the factors that influence adoption. The paper goes on to discuss trust as a concept, its models and how it relates to adoption. It also reports on the results of a survey questionnaire used to determine the factors that influence trust in users. These factors and a comparison of existing trust models were used to propose a new Trust Model for Wearable devices.

It has been clearly shown that mHealth solutions deliver more patient-focused healthcare and improve the overall efficiency of healthcare systems. In addition, these solutions can potentially reduce the cost of providing healthcare in the context of the increasing demands of the ageing populations in advanced economies. These solutions can also play an important part in intelligent environments, facilitating real-time data collection and input to enable various functionalities. However, there are various challenges regarding the development of mHealth solutions: the most important of these being privacy and data security. Furthermore, the use of Cloud Computing is becoming an option for the healthcare sector to store healthcare data, but storing data in the Cloud raises serious concerns. This paper discusses issues related to managing mHealth data in this new context including challenges, security frameworks and requirements, and possible solutions.

Due to the ever growing mobile broadband data traffic over the cellular networks, the small cell deployment is seen as a promising solution for the network operators to increase their network capacity at low cost. This in turn would lead to an increase number of handovers (HOs) for the mobile users, which could affect the device power consumption. In this context, this paper investigates the impact of the HO process on the device energy consumption while performing VoD over a real LTE Small Cell experimental environment. Subjective tests are carried out to study the impact of the video quality on the user perceived QoE. The results show that by changing the quality level of the multimedia stream the energy can be greatly conserved while the user perceived QoE is still acceptable. Furthermore, by adapting to a lower quality level during the HO process, up to 56% energy savings could be achieved.

Service and Buffer Management techniques can be used to ensure Quality of Service (QoS) for different traffic flows according to some specific policies. In this study, a single buffer queuing system is considered to model single and multi-channel, homogeneous wireless network systems such as wireless local area networks (WLANs) and cellular networks. These systems are now being used to carry both voice and data traffic and hence it is important to optimise these systems in an attempt to reduce the blocking, and minimize the latency to acceptable ranges. Since voice packets are delay sensitive, they have the priority to receive service. Also they require smaller buffering capacities, since the response time to voice requests should be below specific values. In addition, in order to reduce retransmission on reliable data connections, data packets are not usurped by incoming voice packets. In this paper, a mathematical analysis of this scenario is explored. The proposed mathematical model is represented by two dimensions, one for incoming voice packets and one for data packets. The models proposed show that it is possible to store incoming voice packets in the queue in case the channel or channels are busy. Both voice and data packets have finite buffering. Incoming voice packets are blocked when the voice buffer or the common queue is full. Therefore there is an added blocking probability of voice due to the presence of data packets in the system when the common queue is full. The analytical model is validated using simulation. The system proposed attempts to provide minimum delay for voice while reducing the disruption to reliable data connections. Numerical results show that, it is possible to attain these goals with reasonable buffer sizes. This study is useful for understanding the trade-offs and thresholds of single and multi-channel systems with voice and data traffic.

This paper presents a new analytical model to enhance the modelling of vertical handover for integrated cellular/WLAN systems. The WLAN system considered is within the coverage area of cellular network, hence users can have a downward vertical handover to the WLAN and/or an upward vertical handover to the cellular network. Recent work on the modelling of these systems using a two-stage model with feedback encountered some complications in terms of handling certain streams. The possibility of having continuous streams which keep on switching between WLAN and cellular systems, may reduce the practicality of the models. The new analytical model presented in this paper restricts certain flows to make sure that the handover calls from the WLAN to the cellular system are not allowed back to the WLAN. Previously proposed analytical models, which do not nullify these streams may not reflect real systems and the results obtained may not be practically applicable especially for such a configuration of cellular/WLAN interaction. A new model is presented with an extra random variable in order to ensure that Markovian property is not violated. Results are presented to show that the new model is a significant improvement but more work is needed to analyse more complex scenarios.

Recent advances in mobile devices and network technologies have set new trends in the way we use computers and access networks. Cloud Computing, where processing and storage resources are residing on the network is one of these trends. The other is Mobile Computing, where mobile devices such as smartphones and tablets are believed to replace personal computers by combining network connectivity, mobility, and software functionality. In the future, these devices are expected to seamlessly switch between different network providers using vertical handover mechanisms in order to maintain network connectivity at all times. This will enable mobile devices to access Cloud Services without interruption as users move around. Using current service delivery models, mobile devices moving from one geographical location to another will keep accessing those services from the local Cloud of their previous network, which might lead to moving a large volume of data over the Internet backbone over long distances. This scenario highlights the fact that user mobility will result in more congestion on the Internet. This will degrade the Quality of Service and by extension, the Quality of Experience offered by the services in the Cloud and especially multimedia services that have very tight temporal constraints in terms of bandwidth and jitter. We believe that a different approach is required to manage resources more efficiently, while improving the Quality of Service and Quality of Experience of mobile media services. This paper introduces a novel concept of Cloud-Based Mobile Media Service Delivery in which services run on localized public Clouds and are capable of populating other public Clouds in different geographical locations depending on service demands and network status. Using an analytical framework, this paper argues that as the demand for specific services increases in a location, it might be more efficient to move those services closer to that location. This will prevent the Internet backbone from experiencing high traffic loads due to multimedia streams and will offer service providers an automated resource allocation and management mechanism for their services.

For communication in Next Generation Networks, highly-developed mobile devices will enable users to store and manage a lot of credentials on their terminals. Furthermore, these terminals will represent and act on behalf of users when accessing different networks and connecting to a wide variety of services. In this situation, it is essential for users to trust their terminals and for all transactions using them to be secure. This paper analyses a number of the Authentication and Key Agreement protocols between the users and mobile terminals, then proposes a novel device authentication protocol. The proposed protocol is analysed and verified using a formal methods approach based on Casper/FDR compiler.

The main feature of the next generation wireless communication systems is the ability to establish ubiquitous and seamless access to various radio access technologies (RATs) and standards. For this reason the integration of cellular and wireless local area networks (WLANs) and performance evaluation of the interaction between these technologies is now an important research area. Modelling such systems for performance evaluation is essential to improve the architecture according to the quality of service (QoS) requirements and performance characteristics. In this paper, an analytical model for performance evaluation of an integrated cellular network and a WLAN is considered. WLAN is deployed inside of the cellular network to support handoffs between cellular networks with higher bandwidth. Such an integrated system can be modelled as a two stage open network. An analytical model is proposed together with an exact solution technique in order to evaluate the performance of an integrated system consisting of a cellular network and a WLAN. A two stage queuing system is considered for this purpose. Numerical results are presented for mean queue length values of cellular system as well as the WLAN.

The use of network-based streaming applications such as YouTube and BBC iPlayer is rapidly increasing. These applications consume data at very high rates and so quality- of-service (QoS) support is necessary to ensure that they do not stall. Since the access pattern of streaming applications is highly sequential, prefetching can be employed to improve overall performance. For network access, clustering can be used to optimize prefetching. In addition, it is necessary to satisfy demand missses promptly or else non-streaming applications will be delayed. Designing a new high-performance storage system to meet these demands require the development of new analytical models. These models will be used to explore new algorithms for network-based storage that can deliver the required QoS to support streaming environments. In this paper a detailed gate-limited bulk service queueing model based on Markov chains is explored and a numeric solution is demonstrated for simple scenarios. The analysis is then applied to a high performance network-based storage server being developed here at Middlesex University. Quantitative results are presented which compare favourably with simulation.

Individual wireless access networks show limitations that can be overcome through the integration of different technologies into a unified platform [i.e., fourth-generation (4G) system]. Nevertheless, the integration of heterogeneous networks poses many challenges such as adding complexity to the processes of deciding when to handoff, selecting the best network, and minimizing roaming effects using appropriate handover methods. This paper presents PROTON, a novel solution that supports decision-making processes related to roaming between heterogeneous technologies. PROTON deploys a formal policy representation model, based on finite-state transducers, that evaluates policies using information from the context to manage mobiles' behavior in a transparent manner, hiding 4G systems' complexities. We blend concepts of autonomic computing into the design of the solution and manage to improve user experience in typical 4G scenarios, while keeping transparency.

Mobile IP enables mobile computers to roam transparently in any network. However, the current proposed protocol specification does not support a suitable handoff mechanism to allow a mobile computer to change its point of attachment from one network to another. This paper describes a handoff mechanism for mobile host, which makes use of Internet protocol version 6 (IPv6) and mobile IP without the need to introduce a new mobility management protocol or make changes to the network infrastructure.

Networked surfaces are surfaces such as desks which provide network connectivity to specially augmented devices, for example handheld computers. When the devices are physically placed on top of the surface, they can connect to different kinds of services-mainly, but not exclusively to send and receive data. This paper discusses challenges in implementing networked surfaces, paying particular attention to data flow issues, focusing on how the various software and hardware entities comprising the surface interact to transport data to and from objects.